You'd never expect it, but roblox has one of the most interesting development platforms. You can throw together some lua code and test everything very quickly. I've even seen someone program a star wars space sim where you can join either the rebels or imperials and fly an xwing, etc. to destroy the other team's capital ship.
I was messing around with the developer studio and copied some lua code to generate a roguelike floorplan and create an actual roguelike level generator in the game in no time.
It also seems to be like F2P developer's wet dream. I was playing that star wars game and there was an option to pay 50 roblux or whatever for "luke's x-wing" - in game.